Vapor phase corrosion inhibitor material

ABSTRACT

A vapor phase corrosion inhibitor formulation comprising a finely divided anhydrous molybdate selected from the group consisting of anhydrous sodium molybdate, anhydrous ammonium dimolybdate, and anhydrous amine molybdates having the structural formula: ##STR1## wherein R 1  is an aliphatic hydrocarbon having up to 7 carbon atoms, and wherein R 2  is either hydrogen or an aliphatic hydrocarbon having up to 7 carbon atoms with these anhydrous molybdates being provided in admixtures with sodium nitrite and benzotriazole. The formulations of the present invention have been found to be particularly desirable as a vapor phase corrosion inhibitor when in contact with the environs of metals susceptible to corrosion including, for example, iron, steel, copper, and alloys such as alloys of iron, copper, and the like. In a preferred embodiment, the amine-molybdate compounds are those amine-molybdates derived from dicyclohexylamine, 2-ethylhexylamine, and cyclohexylamine. The resultant amine-molybdates have vapor pressures which contribute to appropriate protection against corrosion, as well as a continued or ongoing availability of that protection, and when provided in admixture with sodium nitrite and benzotriazole, find particular applicability for extrusion with polyolefin films such as polyethylene and polypropylene, and with such films being capable of forming laminates with metallized second film layers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation-in-Part of our co-pending application Ser. No.07/417,238, filed Oct. 5, 1989, now abandoned, entitled "VAPOR PHASECORROSION INHIBITOR MATERIAL", which in turn was a Continuation-in-Partof application Ser. No. 07/235,120, filed Aug. 23, 1988, entitled "VAPORPHASE CORROSION INHIBITOR MATERlAL", now abandoned.

FIELD OF THE INVENTION

The present invention relates to a formulation which is particularlyadapted for use as a vapor phase corrosion inhibitor, the material beinguseful for either inhibiting the corrosion of the metallic items and/orpassivating the surfaces thereof, the formulation being particularlyadapted for direct incorporation within synthetic resinous films throughextrusion or deposition into a film, such as into an olefinic film,polyethylene, or the like. Specifically, the compositions of the presentinvention comprise a vapor phase corrosion inhibitor selected from thegroup consisting of anhydrous sodium molybdate, an anhydrous ammoniumdimolybdate, and mixtures of such molybdates with sodium nitrite andbenzotriazole, with these compositions providing a vapor phase corrosioninhibitor which may be extruded with a film material and placed withinthe confines of an enclosure housing the item being protected.Alternatively, the materials may be placed within packages containingitems which are to be protected from corrosion. For most purposes,anhydrous mixtures of certain molybdates including anhydrous sodiummolybdate, ammonium dimolybdate and amine molybdates along with mixturesof such molybdates with sodium nitrite and benzotriazole are preferredfor these applications, with this mixture further being preferablyextruded into polyethylene film at a rate of from between about 2percent and 3 percent by weight.

As an added feature of the invention, film materials extruded with theformulations of the present invention may, in turn, be laminated to asecond metallized film, such as, for example, metallized polyethyleneterephthalate. The combined laminate provides a means to reduce and/oreliminate static build-up in or along the film, and accordingly improvesthe properties of the film when employed as an enclosure.

BACKGROUND OF THE INVENTION

In commerce and industry today, the useful life of corrodible items maybe extended and/or preserved by providing corrosion inhibitors whichprotect the corrodible item from the adverse effects of its ambientenvironment. Corrosion inhibitors, particularly vapor phase corrosioninhibitors, have been found useful in protecting certain corrodibleitems against reaction with elements or compounds which may be foundwithin their environment, and thereby losing their effectiveness,reducing their useful life, or otherwise diminishing their value. Suchprotection is typically needed during times of packaging, handling,shipment, or during end use. Elements or compounds which are normally ofprimary concern are gases such as oxygen, water vapor, sulfides, carbondioxide, and the like. The formulations of the present invention findparticular application in the preparation of packaging material,particularly through in-situ extrusion of the material with such films,with the films thereafter forming an envelope or other enclosure aboutthe article being protected. These films may also be employed as amember of a multi-layer laminate including a metallized film having goodtear resistant properties such as stress-oriented polyethyleneterephthalate containing a vapor deposited film or layer of metallicaluminum. Such films are commercially available and are commonlydesignated as "aluminized" films.

Among the common indications of corrosion manifested in useful metallicarticles are oxidation, pitting, tarnishing, mottling, or discolorationof the surfaces of these items These manifestations occur in thearticles, particularly when exposed to oxygen and in either gaseous orliquid phase. Additionally, sulfides may present corrosion or tarnishingproblems as well. Inasmuch as both oxygen and water, including watervapor, occur normally and are available in nature, it is normallynecessary to take precautions against corrosion when packaging metallicitems for shipment, or when subjecting such items to normal use. Metalswhich are frequently found to be susceptible to corrosion under normalatmospheric and ambient conditions are iron, steel, copper, brass,aluminum, silver, and alloys of these metals. The formulations of thepresent invention are particularly useful in providing protection toboth ferrous and non-ferrous metals, including such non-ferrous metalsas aluminum, copper and brass. Care must frequently be taken to protectarticles fabricated from such metals, even when their surfaces have beentreated so as to be provided with sacrificial or aesthetic coatings ofzinc or cadmium on their surfaces. Such sacrificial or aestheticcoatings are, of course, in wide use, but restrictions of use of thesematerials may appear from time to time due to their potentialcontribution to pollution or the like. Accordingly, means must beprovided to find alternate techniques for the protection and/orpreservation of metallic articles.

In the past, it has been known to provide a package or other enclosurewhich includes one or more inhibiting compounds along with thecorrodible item or items to be protected. Additionally, articles havebeen protected by means of utilization of protective coatings in theform of solids, liquids, greases, or pastes, however such coatings tendto be temporary in nature and further present certain disadvantages tonormal handling and packaging. Furthermore, removal of such protectivecoatings may present problems either due to incomplete removal, or thecosts of such removal. The present invention finds application as acomponent which may be co-extruded, with the film forming the enclosureabout the article being protected.

Solid phase and liquid phase compounds have been used in the past toprovide a source of vapor phase corrosion inhibitors. These materialstypically undergo either evaporation or sublimation so as to provide thesubstantially constant availability of the inhibitors. In other words,vapor phase corrosion inhibitors typically emit vapors which protectcorrodible surfaces through the deposition or condensation of aprotective film or coating upon the surface. In order to be assured thata constant supply of inhibitor be present, adequate quantities of thesolid phase or liquid phase corrosion inhibiting compounds must beprovided, with the corrosion inhibiting compounds being released at oradjacent the location where needed.

When a laminate is formed in which one layer comprises a heat sealablefilm such as polyethylene with compounds of the present inventionextruded in-situ, and with a second layer being a material such asmetallized stress-oriented polyethylene terephthalate, a desirablecombination of properties are achieved. Specifically, the polyethylenefilm layer retains its conventional heat sealing properties, while thestress-oriented polyethylene terephthalate provides a tear-resistantproperty. The metallized layer is utilized to reduce and/or eliminatestatic build-up, thereby further enhancing the properties and qualitiesof the laminate. Stress-oriented polyethylene terephthalate is normallybiaxially oriented, and is, of course, commercially available.

SUMMARY OF THE INVENTION

In accordance with the present invention, a solid phase material hasbeen found which provides a source of vapor phase corrosion inhibitingmaterial, with the vapor pressure of the material being balanced withthe quantities normally required to be emitted for effective and longterm protection of the metallic surfaces being exposed for treatment.The formulations of the present invention provide for emission of vaporsin a concentration which is appropriate for strong protection of themetallic surfaces, and yet at a rate sufficiently low so as to providefor relatively long-lasting and long-term effective economic treatment.The formulations of the present invention are compatible with and may beextruded or otherwise deposited with synthetic resinous films, such asaliphatic hydrocarbon or olefinic films such as polyethylene andpolypropylene. Such films may be incorporated with other films in alaminate, and in particular may be combined with a metallized film so asto enhance the static elimination and mechanical properties of thecomposite.

Additionally, the vapor phase corrosion inhibitors of the presentinvention have been found to produce little, if any, visible residue Thelack of residue enhances the utility of the materials, inasmuch aslittle, if any, mechanical or electrical problems result from thecontinuous use of these materials.

Typical corrosion inhibiting articles and materials used in the past aredisclosed in Miksic et al U.S. Pat. No. 4,051,066 and Miksic et al U.S.Pat. No. 4,275,835.

The formulations of the present invention have been found to beparticularly well adapted to be employed as an extrudate with filmsfabricated from aliphatic hydrocarbon such as polyethylene andpolypropylene. For facilitating such extrusion operations, anhydrousmolybdates such as ammonium dimolybdate, sodium molybdate and aminemolybdates are utilized. Generally speaking, the formulations of thepresent invention are utilized for retention and/or packaging withinmodestly porous envelopes or other enclosures formed of plastic film orplastic foam. Typically, those certain enclosures disclosed and claimedin the Miksic et. al. U.S. Pat. Nos. 4,051,066 and 4,275,835, asidentified hereinabove, are well adapted for use with the formulationsor compounds of the present invention. Also, when extruded with a heatsealable film such as polyethylene, a metallized (aluminized) layer suchas biaxially stress-oriented polyethylene terephthalate may be employedto enhance the mechanical properties of the overall arrangement.Techniques for laminating these films together are, of course, wellknown in the art.

In accordance with the present invention, the vapor phase corrosioninhibitors which have been found particularly desirable for use incombination with metallic surfaces susceptible to corrosion compriseanhydrous sodium molybdate [Na₂ Mo O₄ ], anhydrous ammonium dimolybdate[(NH₄)₂ Mo O₄ ], or an anhydrous amine-molybdate having the generalstructural formula: ##STR2## wherein R₁ is an aliphatic hydrocarbonhaving up to 7 carbon atoms, and wherein R₂ is either hydrogen or analiphatic hydrocarbon having up to 7 carbon atoms. The preferred aminemolybdates of this component of the present invention areamine-molybdates derived from the group consisting of dicyclohexylamine,2-ethylhexylamine, and cyclohexylamine. Such molybdates are readilysynthesized and can be prepared in anhydrous form without requiringunusual processing or handling problems. As indicated above, thesemolybdates are utilized in anhydrous form when extruded with the film,and are employed in a mixture in combination with sodium nitrite andbenzotriazole. Alternatively, anhydrous sodium molybdate and ammoniumdimolybdate may be utilized in combination with sodium nitrite andbenzotriazole In use, these materials provide a highly desirable balancebetween continuous emission from the solid phase, with this emissionbeing at a rate sufficiently low so as to provide for relativelyeffective long-term and economic protection and treatment.

It is therefore a primary object of the present invention to provide animproved vapor phase corrosion inhibitor which is particularly adaptedfor use in the protection of metallic surfaces exposed to environmentswhich are corrosive to the exposed surfaces.

It is a further object of the present invention to provide an improvedvapor phase corrosion inhibitor which is formulated so as to possess avapor pressure or other property which allows transport of the inhibitorto the metal surface appropriate for transport of appropriate quantitiesof the inhibitor from solid phase in the film to the metal surface, withthe balance of the inhibitor being retained in the film, to provide acontinuous supply of emitted corrosion inhibiting material.

It is yet a further object of the present invention to provide animproved vapor phase corrosion inhibitor substance which is formulatedso as to be capable of extrusion with conventional aliphatic hydrocarbonresinous films such as polyethylene, polypropylene, and the like.

It is still a further object of the present invention to provide animproved vapor phase corrosion inhibitor substance which is formulatedso as to be capable of extrusion with conventional heat sealable filmssuch as polyethylene, with such polyethylene films being, in turn,laminated to a metallized second film so as to enhance mechanicalproperties as well as static elimination properties of the compositelaminate.

Other and further objects of the present invention will become apparentto those skilled in the art upon a study of the following specification,appended claims, and accompanying drawing.

IN THE DRAWING

The figure is a cross-sectional view of a typical laminate prepared inaccordance with the present invention, with the center or metallizedlayer being shown in somewhat exaggerated form due to limitations ofdraftsmanship.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In accordance with the preferred embodiment of the present invention, aparticularly useful vapor phase corrosion inhibitor for extrudedpolyethylene film includes a mixture of either anhydrous sodiummolybdate, anhydrous ammonium dimolybdate, or amine molybdates, togetherwith sodium nitrite and benzotriazole. Specifically, in a particularlypreferred embodiment, a mixture is provided in the followingformulation:

    ______________________________________                                        Component          Percent by Weight                                          ______________________________________                                        Anhydrous sodium molybdate                                                                       70%                                                        Sodium nitrite     25%                                                        Benzotriazole       5%                                                        ______________________________________                                    

This mixture is particularly effective when extruded into polyethylenefilm at a rate of 2% by weight. Effective mixtures have been found whenextruded into polyethylene film at a rate of up to 3% by weight.

In the formulation provided above, the useful range of the componentsmay be set forth as follows:

    ______________________________________                                        Component          Percent by Weight                                          ______________________________________                                        Anhydrous sodium molybdate                                                                       65%-75%                                                    Sodium nitrite     22%-28%                                                    Benzotriazole      4%-6%                                                      ______________________________________                                    

These ranges may be found useful for certain applications.

While there are various techniques that may be employed for providingthe appropriate extrudate including, for example, polyethylene and avapor phase corrosion inhibitor of the type described herein, oneparticular technique has been found to be particularly useful.Specifically, the formulation is formed and rendered as uniform aspossible, and passed through the barrel of a conventional extruder toform a master batch. The resultant master batch is then chopped andrendered into pellet form. These pellets are, in turn, extruded as thefilm containing a vapor phase corrosion inhibitor of the type described.

In order to describe alternate materials useful in connection with thepresent invention, the synthesis of three amine-molybdate compounds willbe described hereinbelow, it being understood that each resultantcompound possesses appropriate physical and chemical properties in itsanhydrous form so as to be highly useful in connection with the variousaspects of the present invention.

The aliphatic amines employed are from the group consisting ofdicyclohexylamine, 2-ethylhexylamine, and cyclohexylamine, it beingunderstood that other aliphatic amines within this general category maybe found useful as well.

AMINE-MOLYBDATE "A"

Pursuant to this embodiment, dicyclohexylamine having a molecular weightof 181.36 and the empirical formula C₁₂ H₂₃ N is employed. The methodand procedure set forth in Example I hereinbelow is followed.

EXAMPLE I

A formulation is prepared with the following components:

    ______________________________________                                        Component          Percent by Weight                                          ______________________________________                                        Dicyclohexylamine  10%                                                        Phosphoric acid     4%                                                        Water              36%                                                        Aqueous solution of ammonium                                                                      50%.                                                      molybdate (20%)                                                               ______________________________________                                    

The 20% ammonium molybdate solution is prepared by adding puremolybdenum trioxide to a 5% aqueous solution of ammonium hydroxide. ThePh of the resulting solution is normally in the range of 7.5 to 8.5. Thedicyclohexylamine, phosphoric acid and water are mixed together to forma neutral to slightly alkaline solution, the pH being in the range of7.5 to 8.5. The 20% aqueous solution of ammonium molybdate is thenadded. The reaction that occurs is a simple displacement reaction inwhich a white powdery precipitate is formed upon addition of theammonium molybdate solution. Following the completion of the reaction,the mixture is cooled to approximately 60° F., after which theprecipitate is filtered, washed, and dried until the anhydrous form isobtained. The anhydrous finished product is a fine white powder havingthe following structural formula: ##STR3## wherein R₁ and R₂ arecyclohexyl radicals.

AMINE-MOLYBDATE "B"

Pursuant to this embodiment, 2-ethylhexylamine having a molecular weightof 129.2 and the empirical formula C₈ H₁₉ N is employed. The method andprocedure set forth in Example II hereinbelow is followed.

EXAMPLE II

A formulation is prepared with the following components:

    ______________________________________                                        Component          Percent by Weight                                          ______________________________________                                        2-ethylhexylamine    5%                                                       Phosphoric acid    2.5%                                                       Water              67.5%                                                      Aqueous solution of ammonium                                                                      25%.                                                      molybdate (20%)                                                               ______________________________________                                    

The 20% ammonium molybdate solution is prepared as set forth in ExampleI hereinabove. The 2-ethylhexylamine, phosphoric acid and water aremixed together to form a neutral to slightly alkaline solution, the pHbeing in the range of 7.5 to 8.5. The 20% aqueous solution of ammoniummolybdate is then added. The reaction that occurs is a simpledisplacement reaction in which a white powdery precipitate is formedupon addition of the ammonium molybdate solution. Following thecompletion of the reaction, the mixture is cooled to approximately 60°F., after which the precipitate is filtered, washed, and dried until theanhydrous form is obtained. The anhydrous finished product is a finewhite powder having the following structural formula: ##STR4## whereinR₁ is a 2-ethylhexyl radical and R₂ is hydrogen.

AMINE-MOLYBDATE "C"

Pursuant to this embodiment, cyclohexylamine is employed in thepreparation of cyclohexylamine-molybdate. Cyclohexylamine having amolecular weight of 99.17 and the empirical formula C₆ H₁₁ NH₂ isemployed. The method and procedure set forth in Example III hereinbelowis followed.

EXAMPLE III

A formulation is prepared with the following components:

    ______________________________________                                        Component         Percent by Weight                                           ______________________________________                                        Cyclohexylamine   20%                                                         Molybdenum trioxide (pure)                                                                      13%                                                         Water              67%.                                                       ______________________________________                                    

The water, molybdenum trioxide and cyclohexylamine are mixed togetherall at once. While mixing, the solution is heated to approximately 175°F. When the solution becomes clear, the mixture is cooled to 60°-70° F.,whereupon a grey-white precipitate forms. The precipitate is filtered,washed and dried until the anhydrous form is obtained. The anhydrousfinished product is a white crystalline powder with the followingstructural formula: ##STR5## wherein R₁ is a cyclohexyl radical andwherein R₂ is hydrogen.

GENERAL COMMENTARY

The amine-molybdates as set forth above are, of course, employed in theanhydrous form. It has been found that such molybdates, when employed inthe anhydrous form, will be readily incorporated into olefinic filmssuch as polyethylene and polypropylene. Effective mixtures of theamine-molybdates are normally formulated utilizing 70% by weightanhydrous aminemolybdate of the type shown in Examples A, B and C above,25% sodium nitrite and 5% benzotriazole. As indicated in connection withsuch formulations discussed above utilizing anhydrous sodium molybdate,these formulations incorporate amine-molybdates A, B or C, are extrudedinto polyethylene film at a rate of between 2% and 3% by weight.

In accordance with the examples, the aliphatic amine may be present inan amount ranging from between about 5% and 20%. In the interests ofcompleteness of the reaction involved, it has been found thatapproximately 10% by weight of the aliphatic amine produces a desirableend product. The reactions involved occur quite rapidly and have beenfound to go substantially to completion at room temperature.

While dicyclohexylamine, 2-ethylhexylamine, and cyclohexylamine havebeen indicated as the most desirable materials, it will, of course, beappreciated that certain conditions of end use along with certain otherconsiderations and parameters may dictate that somewhat smalleraliphatic chain lengths be employed. For example, use of the material insomewhat cooler environments may render it desirable to utilizematerials having a somewhat shorter chain length in order to achieve anappropriate degree of sublimation while exposed to ambience Otherconsiderations may indicate utilization of such shorter chain lengths,as well.

As has been indicated hereinabove, and with attention being directed tothe figure of the drawing, the vapor phase corrosion inhibitors of thepresent invention are well adapted for extrusion with resinous filmmaterial typically employed in the packaging industry. When employed asa member or layer of a laminate, and with continued attention beingdirected to the drawing, the film generally designated 10 includes afirst layer of plastic film 11 having a metallic or metallizing layer 12deposited, thereon. Layer 13 of laminate 10 is impregnated with thecompositions of the present invention, with the solid particles beingintroduced into the film through co-extrusion techniques. For example,the aminemolybdate of Example I is prepared, and introduced as a finewhite powder into conventional polyethylene film. This impregnated filmis, in turn, laminated to the metallized layer 12 of film 11 so as toform the composite. Laminating techniques for such films are, of course,well known in the art. Metallized films of biaxially orientedpolyethylene terephthalate are readily bonded to and laminated withpolyethylene films of the type shown at 13.

Vapor phase corrosion inhibitor compounds of the present invention arealso well adapted for retention and/or packaging within modestly porousenvelopes or other enclosures. These envelopes may be formed of plasticfilm or plastic foam, or alternatively, may be fabricated fromcellulosic products such as paper or the like. In addition to beingretained and/or packaged within envelopes or enclosures, the materialmay be placed upon or within an appropriate substrate formed of eithersynthetic resin or cellulosic materials. Typical examples of usefulmaterial include polyethylene, polypropylene, paper, and the like. Whenpaper is employed, it is preferred that the drying operation beundertaken so as to provide reasonably anhydrous amine-molybdatematerials. As a still further alternative, the vapor phase corrosioninhibitors of the present invention may be extruded or co-extruded withsynthetic resin materials such as, for example, polyethylene,polypropylene, or the like. Conventional extrusion or co-extrusiontechniques may be employed in this regard.

It will be appreciated, therefore, that examples provided herein are forpurposes of illustration only and are not to be regarded as arestriction upon the scope of the claims, inasmuch as those skilled inthe art may depart from these specific examples without actuallydeparting from the spirit and scope of the present invention.

What is claimed is:
 1. A vapor phase corrosion inhibitor in combinationwith an article comprised of a resinous film wherein said inhibitorcomprises a mixture having the following formulation:

    ______________________________________                                        Component         Percent by Weight Range                                     ______________________________________                                        Sodium nitrite    22%-27%                                                     Benzotriazole     4%-6%                                                       An anhydrous molybdate selected                                                                 65-75%.                                                     from the group consisting of                                                  sodium molybdate, ammonium                                                    dimolybdate, amine molybdates                                                 and mixtures thereof                                                          ______________________________________                                    


2. A vapor phase corrosion inhibitor as defined in claim 1 beingparticularly characterized in that the mixture has the followingformulation:

    ______________________________________                                        Component           Percent by Weight                                         ______________________________________                                        Sodium nitrite      25%                                                       Benzotriazole        5%                                                       An anhydrous molybdate selected                                                                    70%.                                                     from the group consisting of                                                  sodium molybdate, ammonium                                                    dimolybdate, amine molybdates                                                 and mixtures thereof                                                          ______________________________________                                    


3. A vapor phase corrosion inhibitor comprising, in combination: (a) asolid substrate supporting vapor phase corrosion inhibitor solids havingthe following formulation:

    ______________________________________                                        Component         Percent by Weight Range                                     ______________________________________                                        Sodium nitrite    22%-28%                                                     Benzotriazole     4%-6%                                                       An anhydrous molybdate selected                                                                  65%-75%.                                                   from the group consisting of                                                  sodium molybdate, ammonium                                                    dimolybdate, amine molybdates                                                 and mixtures thereof                                                          ______________________________________                                    


4. The vapor phase corrosion inhibitor as defined in claim 3 beingparticularly characterized in that said substrate comprises an aliphatichydrocarbon film selected from the group consisting of polyethylene andpolypropylene, and wherein said vapor phase corrosion inhibitor solidsare retained within said substrate through extrusion, with said filmwhile said film is being formed.
 5. The vapor phase corrosion inhibitoras defined in claim 4 wherein said vapor phase corrosion inhibitorsolids are included in said film in the range of from between 2% and 3%by weight.
 6. A vapor phase corrosion inhibitor in combination with anarticle comprised of a resinous film wherein said inhibitor comprises asubstantially anhydrous amine molybkate in powder form and having thestructural formula: ##STR6## wherein R₁ is a 2-ethylhexyl radical andwherein R₂ is either hydrogen or an aliphatic hydrocarbon having up to 7carbon atoms.
 7. The vapor phase corrosion inhibitor as defined in claim6 being particularly characterized in that R₂ is a cyclohexyl radical.8. A vapor phase corrosion inhibitor package comprising, incombination:(a) a porous modestly permeable envelope enclosing asubstantially anhydrous amine-molybdate in powder form and having thestructural formula: ##STR7## wherein R₁ is an aliphatic hydrocarbonhaving up to 7 carbon atoms, and wherein R₂ is either hydrogen or analiphatic hydrocarbon having up to 7 carbon atoms.
 9. The vapor phasecorrosion inhibitor package as define din claim 8 being particularlycharacterized in that R₁ and R₂ are 2-ethylhexyl radicals.
 10. A vaporphase corrosion inhibitor comprising, in combination:(a) a substratesupporting a substantially anhydrous amine molybdate thereon, theanhydrous amine molybdate in powder form and having the followingstructural formula: ##STR8## wherein R₁ is an aliphatic hydrocarbonhaving up to 7 carbon atoms, and wherein R₂ is either hydrogen or analiphatic hydrocarbon having up to 7 carbon atoms.
 11. The vapor phasecorrosion inhibitor as defined in claim 10 being particularlycharacterized in that said substrate comprises an aliphatic hydrocarbonfilm selected from the group consisting of polyethylene andpolypropylene, and wherein said anhydrous amine molybdate is retainedwithin said substrate through extrusion of the said anhydrous aminemolybdate with the film formation.
 12. A laminate consisting of firstand second film layers bonded to a central metallic layer to form acomposite structure and wherein:(a) said first film comprises asubstrate of an aliphatic hydrocarbon film selected from the groupconsisting of polyethylene and polypropylene having an anhydrous aminemolybdate retained therewithin through extrusion, said anhydrous aminemolybdate having the following structural formula: ##STR9## wherein R₁is an aliphatic hydrocarbon having up to 7 carbon atoms, and wherein R₂is either hydrogen or an aliphatic hydrocarbon having up to 7 carbonatoms; and (b) said second film comprises a layer of biaxiallystress-oriented polyethylene terephthalate.
 13. The laminate as definedin claim 12 being particularly characterized in that said centralmetallic layer is a film of aluminum deposited upon the surface of saidpolyethylene terephthalate film.